1. Field of the Invention
The present invention relates to a claw-pole motor.
Priority is claimed on Japanese Patent Application No. 2005-306800, filed Oct. 21, 2005, the content of which is incorporated herein by reference.
2. Description of the Related Art
In an example of known claw-pole motors, stator rings assigned to a plurality of phases are stacked along their common axis, annular windings are installed in winding attachment holes which have an annular form and are formed between adjacent stator rings along the axis, and claw-shaped induction poles protruding inward or outward in radial directions are provided at the stator ring of each phase. The induction poles assigned to each phase are sequentially arranged along the circumference of the stator rings and also face an outer (or inner) peripheral face of a rotor, so as to commonly use the magnetic path of each phase without varying the flux linkage of each phase (see Japanese Unexamined Patent Application, First Publication No. 2005-117743).
In the above example of the claw-pole motor, magnetic resistance between two phases corresponding to the stator rings which are arranged at both ends along the axis is larger than the magnetic resistance between any other two phases, thereby producing inconsistency in inductance of each phase. If the electric current of each phase has a phase shift due to such inconsistency in inductance, the power factor and the torque constant of the motor are degraded in normal vector control which has a premise that the phase difference between the electric currents of adjacent phases is defined as “2π/3=120 degrees.”
With respect to the above problem, in order to perform drive control of the claw-pole motor after correcting the phase shift due to the inconsistency in the inductance of each phase and making the amplitude and phase of the current of each phase consistent, a specific control device for executing complex control processes is necessary, which reduces flexibility of the control device to be widely used.